Otitis media (OM) is a common disease in infants and children. While each year between 3 and 5 billion dollars are spent in the United States on the management of this disease, few treatments are recognized as effective. The well-supported immediate cause of OM is a preceding or concurrent viral upper respiratory tract infection (vURI) and it has been suggested that most episodes of OM could be prevented by preventing vURIs or by early treatment of those infections prior. In recent years, effective vaccines and antivirals have been marketed that prevent or treat infection with some of the viruses that cause OM, and others are in development. However, the judicious introduction of these possible interventions for OM depends on a number of factors not known at present. These include, for each virus that can cause vURIs: the natural history of OM, the temporal pattern relating vURIs and OM presentations, the co-incidence of OM and vURI and the percent of vURI and OM episodes that are symptomatic, among others. Also, to avoid over-treatment of patients at little risk for OM, a definition of patient characteristics that predispose to OM is important. In the proposed study, we will acquire this information. Specifically, we will study young children in their home environment throughout the typical cold-flu months by daily symptom recording and assessment of middle ear status, weekly ear and nose examinations and monthly bacterial and virus assays; and, if they develop signs and symptoms of either a cold-like illness or OM, we will re-evaluate these children in the clinic for confirmatory diagnosis of OM, vURI and etiological virus. For all enrolled children, we will determine their genotype for the production of certain cytokines that were suggested to influence disease expression during a vURI and/or the development of OM. During vURIs, we will also determine the types of cytokines that are produced in the nose, and relate these to OM incidence. From this close follow up of children for OM and vURI, we will estimate the parameters needed to define the expected efficacy and efficiency of different strategies to prevent OM caused by vURI. The role of cytokine genotype and expression pattern in predisposing to the development of OM as a complication of vURI may delineate possible "at risk" groups for targeted intervention. These results will be used in the design of future studies that prevent OM by moderating vURI pathogenesis.